The invention relates to single-spindle machine, method and apparatus for carrying out mechanical workings, preferably by shaving removal on elongated mechanical parts, such as general semi-worked pieces.
Prior art comprises machine tools for working profiled elements, for example made of aluminium or PVC, wherein the profiled elements, consisting of bars often having even remarkable length, are arranged in a fixed working position with respect to a base-frame and are kept in that position through a plurality of fastening clamps. A moving trolley, carrying motorized groups of tools, is positioned at pre-established, longitudinally consecutive, cross sections of the profiled element in order to perform on each section the required mechanical workings.
A first limitation of these known machines consists in that, the downwards face of the profiled element to be worked, i.e. the one adjacent to the machine bed, is poorly accessible and then difficult to be worked, since the base-frame overall dimensions hamper tool approach to the profiled element.
Workings on the face adjacent to the machine bed are performed through operating heads with mechanical transmission of motion, which are placed faraway from the supports and are therefore not very accurate. However, these operating heads can only perform relatively simple operations.
Consequently, if the profiled element has to be subjected to complex workings also on the face adjacent to the machine bed, it is necessary to position it again on the machine after rotating it of a suitable angle about its own longitudinal axis, so that the face, which was previously difficult to be machined, is now easily accessible by a suitable tool, or group of tools.
A further limitation of such machines can be found in the heavy impact of loading and unloading idle times on the working cycle: actually, when the planned working sequence on a single profiled element is finished, it is necessary to pick it up in order to clear the working position on the machine and to carry in that position another element which has still to be worked; the already worked element clearing phase and the still to be worked element positioning phase, during which it is not possible to carry out any machining on the profiled element, imply a remarkable waste of time, particularly ifxe2x80x94as it often happensxe2x80x94the elements to be worked are considerably voluminous.
In addition, clamps are known for locking the profiled elements to be worked on the bed of such machines, wherein locking of each clamp is provided by feeding compressed air to pneumatic actuating members that keep each clamp in a pre-established position while locking it on the guides.
These clamps have the disadvantage of requiring a complex air supplying circuit and furthermore, if the air pressure accidentally decreases, the clamps result substantially free to move along the guides, which implies risks of failures and accidents for personnel in charge.
Furthermore, the known machines require that the profiled element is at first placed in a working station, subsequently worked in that station and then unloaded. This implies the disadvantage that the profiled element machining has to be stopped during the positioning and unloading operations of the profiled element from the working station: that produces excessively long cycle times.
Therefore, the problem arises of improving the known systems for carrying out mechanical workings on profiled elements. More in particular, it is desirable that it is possible to carry out the required workings on every face of the profiled element.
Furthermore, it is desired to find a more efficient working system for profiled elements, i.e. wherein the impact of loading and unloading times is remarkably reduced.
In addition, it is desired to find a new clamps actuation structure which is more reliable and simple.
In a first aspect of the invention, a machine is provided for carrying out mechanical workings preferably by shaving removal, comprising frame means arranged for receiving a semi-worked piece to be worked, the semi-worked piece having a cross section exhibiting dimensions remarkably smaller than the length of the piece measured along its own longitudinal axis, said semi-worked piece being arranged with said longitudinal axis along a working axis in a working station, clamp means arranged at a plurality of cross sections of said semi-worked piece for locking said semi-worked piece in said working station, tool means arranged for carrying out workings on faces of said semi-worked piece, characterized in that, supporting means is provided to which said semi-worked piece is fixed by said clamp means, said supporting means being suitable to be rotated about a service axis.
In a version, the service axis is coincident with said working axis.
In this case, as supporting means is provided, it is possible to machine all the faces of the semi-worked piece, since, after carrying out mechanical workings on the semi-worked piece faces directly accessible by tool means, it is possible to rotate the, supporting means in order to work the remaining face or faces, without removing the semi-worked piece from the working station.
In a further version, the service axis can be positioned parallel to said working axis.
This allows the supporting means to be equipped with more than one semi-worked piece; it is therefore possible, for example, after completing workings on a semi-worked piece, to rotate the supporting means in order to bring the already worked semi-worked piece into an unloading station, and simultaneously bring a still to be worked semi-worked piece into the working station.
Advantageously, the supporting means comprises first supporting means arranged for rotating the semi-worked piece about said working axis and second supporting means arranged for rotating the first supporting means, together with the semi-worked piece associated thereto, about a service axis parallel to said working axis.
This allows all the faces of the semi-worked piece to be machined without removing it from the working station, the already worked semi-worked piece to be quickly unloaded from the working station and a still to be worked semi-worked piece to be loaded in said station.
Advantageously, the working axis and the service axis are arranged in vertical position.
It is thus possible to obtain a machine for working semi-worked pieces having very reduced plant overall dimensions. Furthermore, such a machine can be easily soundproofed.
If a vertical arrangement for such a machine is provided, the user can collect downwards the shavings produced when machining the semi-worked piece and can remove them in a very simple way.
Finally, in a vertically developed machine, the semi-worked piece to be worked can be positioned in the optimal manner, as, since it is a slender piece, it would show a tendency to bend under its own weight if it were arranged horizontally.
In a second aspect of the invention, clamp means is provided slidably coupled on guide means and arranged for locking a semi-worked piece, at cross sections taken along its length, through pliers means driven by suitable actuating means, characterized in that, said clamp means is provided with mechanical locking means suitable to lock said clamp means onto said guide means.
Since mechanical locking means is used for locking the clamps a greater positioning reliability can be obtained, which prevents a complex and bulky pneumatic circuit for compressed air supplying to be arranged.
In a third aspect of the present invention, a method is provided for working semi-worked elements, comprising placing a semi-worked piece in a working station, characterized in that, substantially simultaneously to said placing it is further provided placing a semi-worked piece to be worked in a loading station and extracting a semi-worked piece already worked from an unloading station.
In this way, the semi-worked piece working cycle is made particularly efficient since auxiliary working steps are performed while semi-worked piece working is in progress, instead of being performed before or after working is carried out as in traditional systems.